Abstract

Background

The sensory neurons and glia of the dorsal root ganglia (DRG) arise from neural crest
cells in the developing vertebrate embryo. In mouse and chick, DRG formation is completed
during embryogenesis. In contrast, zebrafish continue to add neurons and glia to the
DRG into adulthood, long after neural crest migration is complete. The molecular and
cellular regulation of late DRG growth in the zebrafish remains to be characterized.

Results

In the present study, we use transgenic zebrafish lines to examine neuronal addition
during postembryonic DRG growth. Neuronal addition is continuous over the period of
larval development. Fate-mapping experiments support the hypothesis that new neurons
are added from a population of resident, neural crest-derived progenitor cells. Conditional
inhibition of Notch signaling was used to assess the role of this signaling pathway
in neuronal addition. An increase in the number of DRG neurons is seen when Notch
signaling is inhibited during both early and late larval development.

Conclusions

Postembryonic growth of the zebrafish DRG comes about, in part, by addition of new
neurons from a resident progenitor population, a process regulated by Notch signaling.